1. Field of Invention
This invention is directed to an improved method and apparatus for obtaining epithelial cell samples from the outer cervix and endocervix simultaneously, using an adjustable device with dual brushes for the collection and diagnosis of cancer and precancerous lesions.
2. Description of Prior Art
The collection and analysis of cellular samples for the detection of precancerous and cancerous lesions are vital steps in the prevention and treatment of cervical cancer.
The Pap smear has been one of the most simple, minimally invasive and inexpensive innovations in the history of women's health. Adequate sampling of cervical and endocervical cells are critical to accurate diagnosis. It is estimated that at least ⅓ of false-negative Pap smears are due to sampling issues.
A number of devices have been developed to collect samples from the cervix including cotton swabs, wooden and plastic spatulas, and cervical collection brushes with either fine nylon bristles or thick plastic bristles. Such devices are disclosed in U.S. patents to MacLean (U.S. Pat. No. 2,955,591), Antonides (U.S. Pat. No. 3,626,470), Oster (U.S. Pat. No. 3,815,580), Levene (U.S. Pat. No. 3,881,464), Nollon (U.S. Pat. No. 4,127,113), Kist (U.S. Pat. No. 4,700,713), Bayne (U.S. Pat. No. 4,754,764), Stormby (U.S. Pat. No. 4,759,376), Bayne et al. (U.S. Pat. No. 4,762,133), Bayne (U.S. Pat. No. 4,873,992), Mohajer (U.S. Pat. Nos. 5,022,408 and 5,279,307), Sak (U.S. Pat. No. 5,787,891), Lonky (U.S. Pat. No. 6,258,044), Colaianni (U.S. Pat. No. 6,336,905), Edens et al (U.S. Pat. No. 6,521,190), Williams (U.S. Pat. No. 6,612,996), Wallach (U.S. Pat. Nos. 6,387,058 and 6,740,049), and Decker et al. (U.S. Pat. No. 7,413,551). Currently the most effective method for adequate sampling is with a two step process using two instruments, the extended-tip spatula with an endocervical brush.
Nylon endocervical brushes have been proven to collect substantially more cells than original collection devices. They, however, cannot be adjusted in depth to allow for a patient's endocervical length or clinical history such as: stenosis occurring in postmenopausal women, pregnancy, prior cervical therapy, or prior inadequate endocervical sampling. Currently no brush devices contain means for identifying depth of endocervical sampling by displaying incremental markings or measurements.
Inadequate amounts of endocervical cells indicate that the transformation zone, the area that is the source of 90-95% of cervical cytologic atypia, has not been sampled. The location of the transformation zone varies in women, and, depending on factors such as age, genetics, and hormonal status, will migrate higher or lower within the endocervical canal. As a patient's age increases, the transformation zone will commonly be out of reach for the standard length endocervical brush. In a significant number of instances, when the specimens are not adequate because of lack of endocervical cells, the cell sample is less than optimal, and the patient is called for a re-examination. Repeat testing may unduly alarm the patient, and add unnecessary and unjustified medical expenses.
In pregnant patients, the location of the transformation zone may descend, but practitioners may be reluctant to sample deeply enough, or may choose to abandon the endocervical brush altogether. Although certain manufacturers have indicated endocervical brushes are not recommended in pregnant women (post 10-weeks) due to possible clinical complications, other studies have considered this concern to be unfounded. Studies have indicated that the nylon brush yields the highest rate of adequate smears throughout pregnancy, and showed no significant increased risk of serious outcomes with the use of the brush and the spatula. Although the endocervical brush produces more adequate Pap smears in pregnancy, there is currently no way to adjust for the depth of sampling in pregnant patients.
Another disadvantage to the endocervical brush is the lack of a stop or guide preventing the brush from entering too deeply into the endocervical canal. Inexperienced clinicians or medical students may insert the brush far beyond the transformation zone, and unknowingly sample the endometrium. Endometrial cells present on a Pap smear, other than during a menstrual cycle in pre-menopausal women, can have clinical significance to the clinician and patient by prompting an abnormal diagnosis.
Distinct endocervical sampling is also necessary as an increase in cervical adenocarcinoma has been noted, but for unknown reasons. Probable association with Human Papilloma Virus (HPV) types 16 and 18 is suggested. HPV types 16 and 18 account for 70% of all of cervical carcinomas. In the cervix, a typical aceto-white reaction is visibly observed by the clinician in affected areas, but glandular lesions are not visible, even during colposcopy.
Another disadvantage of the endocervical brush is that a large portion of the cell sample is lodged within the bristles of the brush, making it difficult to transfer all of the cells to the slide merely by wiping the bristles against the slide's smooth surface. Valuable diagnostic material is potentially lost, increasing the risk of a false-negative diagnosis. With the popularity of liquid-based cytology for monolayer preparations of cells, the accuracy of the resulting sample is again dependant on the successful and complete transfer of cell samples from the brush bristles to the container of fixative. Typically, the transfer is done by placing the bristled end of the cytology brush within the container holding the fixative solution. The brush is then manually rinsed within the solution in an attempt to dislodge the cells from the bristles. However, the rinsing action within the solution is often insufficient to dislodge or flush out all the cells that are contained on the bristles. On average, 37% of cellular material is lost when the collecting device is discarded, and the more intense the rinsing process, the less the loss of cells.
Another disadvantage is that cervical mucous tends to quickly air-dry unless immediately rinsed in the fixative solution, thickening and binding the cells to the bristles. Rinsing, or using a manual vortex action within the solution alone may not be adequate to release the cells from the bristles.
Some newer collection devices require the physical removal by handling and/or snapping off the brush or the device tip to avoid discarding it. This has a drawback in that a loss and disruption of cellular material by human manipulation occurs when attempting to remove the brush from the shaft. Another drawback is that the device tip typically this has to be removed at the laboratory prior to specimen processing. The shaft of the brush device can also interfere with the pipette tips of an automated pipettor, causing errors in sampling for assays utilizing automation such as molecular based tests for HPV, Chlamydia and Gonorrhea.
Other prior art cytology sampling tools designed to obtain a cellular sample from the cervix may combine both endocervical and outer cervix sampling regions into one device. These devices swab the surface of mucous-covered tissue by softly brushing the mucous layer of the endocervix and outer cervix at the same time. Such devices include brushes that have a contoured flat broom-like head with several rows of flexible plastic bristles arranged in a linear orientation. The center bristles are longer than the bristles on the ends, and the device is inserted into the endocervical canal until the lateral bristles bend against the outer cervix surface. The device is removed and the cells are swabbed across a glass slide, or, alternatively, the entire device is rinsed in a container of fixative solution for liquid-based cytology methods.
Several studies have indicated that a broom-like device with thicker collection bristles have a tendency to provide less than optimal sampling of the endocervix. Certain indications for one such broom-like device indicate rotation only in a clockwise direction. Each individual bristle has a flat and rounded side, and a counterclockwise rotation brings the rounded side in contact with the cervix instead of the flat side, reducing the device's effectiveness of collection.
Debate continues whether “all-in-one” broom-like devices appropriately sample the cervix. While agreement has been reached for sampling the transformation zone, differences in the estimated proximity of the transformation zone and the face of the outer cervix has led to doubt the effectiveness of sampling the endocervix and outer cervix with a broom-like device. It has been reported that broom-like devices appear to under-sample the endocervix, resulting in increased less than optimal Pap smear results based on lack of endocervical component. This may be due to the parallel positioning of the broom's bristles to the endocervical canal, or possibly the broom-like devices do not reach into the cervical opening as far as nylon endocervical brushes.
Another disadvantage of cervical broom-like devices is that although the bristles may be flexible, the clinician cannot manually adjust for different depth sampling of the endocervical canal.
A further disadvantage is that currently no broom-like devices contain means for identifying depth of endocervical sampling by displaying incremental markings or measurements.
Another disadvantage is that the base of the broom-like device is arranged in a linear configuration, requiring additional rotations of the device to sample the entire outer cervix area. Additional rotations of cytology collection devices cause unnecessary abrasion of the cervix surface, adding to patient discomfort and bleeding. Excessive red blood cells in a Pap smear can obscure the view of other diagnostic cells during the microscopic evaluation of the glass slide. A further disadvantage is that studies have indicated that excessive red blood cells introduced to the container of fixative solution may clog the filters of certain liquid-based cytology methods, blocking the epithelial cells from being deposited onto the glass slide.
Another disadvantage of the broom-like device occurs if a glass slide must be prepared instead of using a liquid-based cytology method. Liquid-based cytology methods require specific instruments, machinery, and personnel to process the specimen to the glass slide. This may be costly and prohibitive in parts of the world that are isolated, poor, or lack the benefit of technological advancements. When attempts are made to smear the cells collected from the broom-like device onto the glass slide, the linear base of the device prevents the clinician from rolling the device along the slide's surface. The device must be swept along the surface of the slide similar to a paint brush, and this may prevent the cells that are lodged between the plastic bristles from being transferred to the slide. If the clinician attempts to flatten and bend the plastic bristles onto the glass slide to release material, the endocervical components will be inadvertently mixed with the cervical components. Although it is not required for Pap smears, the definite separation of endocervical cells from cervical cells provides a visual advantage that aids in distinguishing the different cell types during microscopic evaluation.
Although the present cell collection brushes and broom-like devices are well-known and widely used, there continues to be many disadvantages associated with them. Existing brush systems have various drawbacks which may be addressed through the development and use of an improved endocervical and cervical cell sampler. Since it is important to obtain a large enough sample of cells to ensure the chances of detecting abnormal cells in a sample, it would therefore be highly desirable to have a method and device which increases the total number of endocervical and outer cervical cells collected from a patient. Further technological advancements in cytology such as molecular testing for Human Papilloma Virus, the virus responsible for all cervical carcinoma, will require even more cells to be collected in the future. As multiple testing is conducted from the same liquid-based collection container, a sample that is highly-enriched with cellular material would provide more opportunities for disease detection.
Other prior art sampling tools include an apparatus and method for obtaining a transepithelial specimen of a body surface using a non-lacerating technique, but the stiffness of its brush bristles lends itself for tissue sampling and is not appropriate for cytology.
Obvious advantages of this embodiment will become apparent from the detailed descriptions, taken in conjunction with the accompanying drawings.